bài 2
[math]\begin{array}{l}
x = 0 \Rightarrow \dfrac{3}{2} = a - b + \dfrac{c}{2} \Leftrightarrow 2a - 2b + c = 3\\
x = - 1 \Rightarrow \dfrac{3}{2} = \dfrac{a}{4} - \dfrac{b}{2} + c \Leftrightarrow a - 2b + 4c = 6\\
x = 2 \Rightarrow \dfrac{{21}}{4} = a + b + \dfrac{c}{4} \Leftrightarrow 4a + 4b + c = 21
\end{array}[/math]
bấm máy giải hệ ra a, b, c
[math]\left\{ \begin{array}{l}
2a - 2b + c = 3\\
a - 2b + 4c = 6\\
4a + 4b + c = 21
\end{array} \right.[/math]